1. Field of the Invention
The present invention relates to vitreous carbon material and methodology for making vitreous carbon substantially free of pressure-induced cracking and manufacturing-related morphological defects.
2. Description of the Related Art
In the manufacture of vitreous carbon, a variety of manufacturing methods are employed. All of the currently known methods, however, are severely limited in the size of defect-free vitreous carbon material that they can produce.
Specifically, in considering bulk vitreous carbon material of three-dimensional character in an x,y,z-Cartesian coordinate system, where x and y are length and width dimensions, and z is the thickness dimension, the x and y dimensions can be of virtually any size, but the thickness z is effectively limited to no more than about 10 millimeters if defect-free pure vitreous carbon material is to be achieved. Above such thickness, all of the currently known methods for making pure vitreous carbon produce material that is cracked, pitted, chipped (spalled) or otherwise has morphological defects that render it unsuitable for commercial use.
This thickness constraint has severely limited the commercial utility of vitreous carbon for numerous applications for which it otherwise would be highly suitable.
Burton et al. U.S. Pat. No. 5,182,166 describes a process for incorporating a reinforcement material in vitreous carbon to enable large-size composite bodies to be manufactured. Burton et al. U.S. Pat. No. 6,506,482 describes use of metal fiber as a reinforcement medium in vitreous carbon to form a composite that is essentially free of foam and fume indicia, with each of its dimensions being at least 25 millimeters. By adding metal or other reinforcement materials, as described in these patents, larger-sized bodies can be made, but the resulting vitreous carbon is not homogeneous, being adulterated by metal fibers, metal mesh or other necessary reinforcement materials. The presence of such reinforcement in many instances sufficiently alters the chemical, electrical, mechanical, tribological and other properties of the vitreous carbon composite in relation to the pure vitreous carbon materials per se, as to render the resulting composite material unsuitable for the intended use. For example, metal reinforcement elements during the long pyrolytic vitrification process can form metal carbides that are brittle and substantially impair the strength and structural integrity of the composite.
There is accordingly a need for improved vitreous carbon manufacturing processes that enable pure defect-free vitreous carbon material of large size to be economically achieved.